This study examined the T cell responses in the early phase of Leishmania b
raziliensis infection. Cytokine profiles, lymphoproliferative responses, an
d skin test results in 25 patients with early cutaneous leishmaniasis (ECL;
illness duration <60 days) were compared with those in persons with late c
utaneous leishmaniasis (LCL; illness duration >2 months). Absent or low lym
phoproliferative responses were observed in 8 (32%) of 25 patients and an a
bsence of interferon (IFN)-gamma production in 9 (41%) of 22 patients prior
to therapy. IFN-gamma production in ECL (mean +/- SD) was lower than in LC
L (293 +/- 346 vs. 747 +/- 377 pg/mL, respectively; P<.01). In contrast, in
terleukin (IL)-10 production in ECL(mean +/- SD) was higher than in LCL(246
+/- 56 vs. 50 +/- 41 pg/mL, respectively; P <.01),Restoration of lymphopro
liferative responses and IFN-gamma production was achieved when monoclonal
antibody to IL-10 or IL-12 was added to the cultures. These results show th
at T cell responses during early-phase infection are down-regulated by IL-1
0 and may facilitate parasite multiplication.